The machine for dispensing sodas or gasified beverages, such as soft drinks, basically comprises at least one water reservoir and at least one syrup (beverage concentrate) reservoir. The water and syrup flows are independent from each other and refrigerated by an adequate refrigerating system provided at the operational unit of the machine. The water passes through a carbonator, which consists of a refrigerated chamber containing pressurized carbonic gas, which is dissolved in the water, gasifying said water. The gasified water and syrup travel through respective coils, till they reach a dispensing valve, which releases a peripheral flow of gasified water and a central flow of syrup. Said flows are at about 4.degree. C. and mixed in the consumption container, such as a glass.
The operational unit of a soda dispensing machine carries, within a cabinet provided with a lid, a tank containing water, in which there are submersed: the evaporator of a refrigerating unit disposed above the tank; the carbonated water and syrup coils, attached to a coil support or basket; the carbonator; and a stirrer, to provide the circulation of the immersion water in said tank.
In the known soda dispensing machines, the evaporator, which has a generally substantially parallepipedal shape with a square base, is disposed inside the tank, in order to present at least one of its lateral surfaces spaced from the adjacent tank wall, in such a way as to allow the carbonator to be disposed therebetween. The coil basket is peripherally disposed inside the evaporator, with the stirrer being geometrically disposed in the center of the coil basket.
The immersion water of the tank is refrigerated by the evaporator. For this purpose, the evaporator forms on the surface thereof an ice layer, which is melted by said water, the latter transferring to the ice layer an amount of heat corresponding to the latent heat of fusion of the ice, thereby cooling said water.
The several flows, i.e., the water and carbonic gas flows, which are fed to the carbonator, the gasified water flow, supplied by said carbonator and the syrup flows are refrigerated, by immersing the respective tubes and coils in the water of the tank, while the carbonator is refrigerated by a water flow projected through the evaporator against said carbonator, by action of the stirrer.
A good soda should present an adequate level of dissolved gas, so as not to transmit to the consumer the sensation of being flat. Such satisfactory level of gasification basically depends on the perfect operational conditions of the carbonator which, besides receiving the adequately cooled flows of water and carbonic gas, should itself be perfectly cooled.
Such condition is not always fully reached in the prior art equipment. The fact that the carbonator is disposed externally to the evaporator already provides an unfavorable operational condition, since this region is hotter than the inside of the evaporator, usually causing an overpressure inside the carbonator, resulting in the activation of a drain valve, which is disposed on the top thereof, and which liberates an excess of water-air-carbonic gas mixture, to be explained ahead. This drawback, together with a consequent undesirable loss of carbonic gas, is usually minimized by overdimensioning the refrigerating system. Such machines further present a second drawback. When the machine is switched on, but not used for a long period of time, a thick ice layer is formed around the evaporator, creating a barrier to the flow of water from the tank through the evaporator, preventing the carbonator from being adequately refrigerated when the machine is used again to deliver the soda. It should be noted that this problem will be even greater when the refrigerating system is overdimensioned, with the aim to solve the first drawback mentioned above.
Generally, the water to be gasified enters the carbonator, carrying therewith an amount of dissolved air. Since this air is lighter than the carbonic gas, it will be displaced by the latter during the water gasification, accumulating on the top of the carbonator. In order to avoid the air to occupy a large space in the carbonator, preventing the latter from working adequately and avoiding the precise water gasification, the above cited drain valve is manually activated, so as to allow the purgation of said accumulated air.
The arrangement of said valve on the top of the carbonator in the known machines generates additional problems: the purged air carries a large amount of water, which constitutes a potential source of short-circuits when in contact with the electrical system inside the machine. Moreover, said valve is of difficult access, requiring the removal of the external lid of the appliance to be operated.